How does the Washington Post know that Alexander Vindman didn't coordinate with the Ukraine whistleblower?

These two things can be true at the same time: President Trump committed an impeachable offense with regard to his conduct with Ukraine, and the permanent government bureaucracy has actively worked to undermine this president.

The difference between those things is that the first one is a matter of political opinion — Trump committed no crime and hasn’t been accused of one — whereas the second one can be proven true or false even if the national media have shown virtually no interest in exploring it.